In Polymer Electrolyte Fuel Cell system using hydrogen gas as fuel for a fuel cell stack thereof, hydrogen gas unused at the fuel cell stack is returned to a supply line thereof to be recirculated in a closed loop fuel recirculation system. Recirculation of the hydrogen gas thereof provides a hydrogen supply to the fuel cell stack at a rate exceeding consumption rate thereof, stabilizing power generation by the fuel cell stack.
Japanese Patent Application Laid-Open No.2001-266922 discloses a fuel cell system in which unused hydrogen is recirculated by use of an ejector provided on a supply line to the fuel cell.